Battens have previously been used by the applicant in their facade and fascia cladding systems. These battens are sometimes referred to as “top hats” due to their inverted U-shaped cross-section and outwardly splayed edge flanges. The function of these battens or top hats is to provide a planar fixing frame for connection of cladding sheets. As will be appreciated by those skilled in the art, when applying cladding sheets over an uneven surface it is important that the frame on which the cladding sheets are mounted is planar. By the addition of packing materials, and spacers in conjunction with top hat battens, such a planar fixing frame can be obtained.
A known example of a conventional cladding system is shown in FIGS. 1 to 3. FIG. 1 is a front elevational view of a wall 10 covered with a plurality of cladding sheets 11. Each cladding sheet is supported along its longitudinal edges 12 by battens 20. This can be seen more clearly in FIG. 2 which is a cross sectional view through a batten interconnecting two adjacent sheets 11. Each batten is formed by a channel member having a pair of side walls 23 adapted for connection to the frame or wall, to be concealed by means of mounting screws 26 extending through edge flanges 27. An intermediate web 28 forms a platform spaced outwardly from the wall, to support the cladding sheets which are secured by screws 29. The web 28 is of sufficient width to extends across the joint 30 between the two sheets 11. The battens 20 are generally spaced apart to suit the wind loading on the cladding sheets. If required, additional intermediate battens 21 (as shown in FIGS. 1 and 3) may be provided.
The applicants have found that such top hat batten sections allow the main structural framing elements of the wall 10 to be spaced further apart, with the top hat battens spanning the structural elements to provide fixing points for the cladding sheets. It will be appreciated that this provides a substantial cost saving with regard to both the materials and labour required for framing.
Conventional top hat battens, however, have several drawbacks. Firstly, the generally require gaskets 31, backing strips 32 and sealants to provide adequate weatherproofing of the cladding system. Apart from the additional cost associated with such gaskets and backing strips, poor installation techniques may result in misalignment of the cladding sheets and damage to the sheets from over stressing along their edges, as well as inadequate waterproofing. The process is also labour intensive.
Additionally, the generally narrow width of the platform section 28 of the top hat battens requires fasteners to be located close to the sheet edges, as shown in FIG. 2. If such fasteners are located even a few millimetres closer to the sheet edge or if the sheets are not fastened correctly, failure or “break out” of a sheet edge along the line of the fasteners can occur.
Lastly, in use it will be appreciated that stresses can be applied to the cladding sheet either internally or externally which can compromise the strength, weatherproofing or durability of conventional cladding systems. For example, external stress may be applied to a cladding sheet by wind loading or by thermal expansion or contraction of the sub-frame or battens themselves. Internal stresses may arise, for example, from within the fibre reinforced sheet due to moisture movement, carbonation shrinkage etc. In either case, such stresses can lead to premature wear, leakage, or even failure of various elements in the system.
The present invention seeks to overcome or substantially ameliorate one or more of these disadvantages of the prior art, or at least to provide a useful alternative.